When preparing piping bags for pre-filling the bags are usually separated individually from e.g. a continuous web comprising numerous piping bags. The individual bag may then be filled, or strictly speaking pre-filled, with substances in a substantially viscous liquid or fluid form, e.g. foodstuffs, glue, cement, plaster; and subsequently sealed shut. This operation is usually time consuming as one bag at a time must be separated from the web of piping bags and arranged such as to allow for the liquid to be filled in the individual piping bag.
Piping bags made in accordance with WO2005115162A1 may, as disclosed therein, be provided, at its open end, with a weaker welding joint, which is such that upon tearing along the severance mark separating the piping bags along their openable ends, each piping bag remains closed until a user deliberately opens it. This weaker welding joint can be achieved at a low temperature and under mechanical pressure.
While the weaker welding joint is advantageous from a hygiene perspective—the piping bag remains hermetically sealed and free from contaminants until deliberately opened—it may nevertheless present a problem when the piping bag is to be prefilled in an automated pre-filling line, especially when attempting to open the bag using a vacuum-based gripping device. With the hermetic seal, a vacuum on the inside of the bag will require a great force to be applied on the outside for the bag to open. Such a great force may not be possible to apply using a vacuum, especially if the piping bag surface is slightly rough, as the one disclosed in WO2005115162A1.
Hence, there is a need for an improved device and method for opening a piping bag.